MathematicsThe total surface area of a cone of radius r2 and length 2l is ____.

The total surface area of a cone of radius $\frac{r}{2}$ and length 2l is ____.

The total surface area of a cone of radius

\frac{r}{2}

and length 2l is

πr (l + \frac{r}{4})

.
Given, the radius is

\frac{r}{2}

and the length is 2l.
We know that the total surface area of a cone of radius r and length l is

πr (l + r)

\Rightarrow

The total surface area of a cone =

π \frac{r}{2} (2 l + \frac{r}{2})

\Rightarrow

The total surface area of a cone =

πr (l + \frac{r}{4})

Hence, the correct answer is

πr (l + \frac{r}{4})

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